1. School of Mathematics and Statistics, Northwest Normal University, Lanzhou, People's Republic of China
2. Gansu Provincial Research Center for Basic Disciplines of Mathematics and Statistics, Lanzhou, People's Republic of China
3. School of Decision Science, The Hang Seng University of Hong Kong, Hong Kong, Hong Kong
4. Centre of Data Innovation Research, University of Hertfordshire, Hatfield, UK
5. Department of Physics, Astronomy & Mathematics, University of Hertfordshire, Hatfield, UK
6. School of Physics, Engineering & Computer Science, University of Hertfordshire, Hatfield, UK
7. School of Statistics, Renmin University of China, Beijing, People's Republic of China